2005 Dodge Caravan Leaks

2005 Dodge Caravan 100+K miles. There is a redish brown fluid leaking behind front wheel wells on both sides. It does not seem to leak when I park on a flat surface. What could it be and how much does it usually cost to fix it?
I've washed the van several times including the undercarriage. Tried driving without the AC or heater running. Checked all fluid levels which always look fine. Still my driveway has new spots.